The half-Heuslers NbCoSn and NbCoSb have promising thermoelectric properties. Here, an investigation of the NbCo_1+ySn_1−zSb_z (y = 0, 0.05; 0 ≤ z ≤ 1) solid-solution is presented. In addition, the p-type doping of NbCoSn using Ti and Zr substitution is investigated. Rietveld analysis reveals the gradual creation of Nb vacancies to compensate for the n-type doping caused by the substitution of Sb in NbCoSn. This leads to a similar valence electron count (∼18.25) for the NbCo_1+ySn_1−zSb_z samples (z > 0). Mass fluctuation disorder due to the Nb vacancies strongly decreases the lattice thermal conductivity from 10 W m⁻¹ K⁻¹ (z = 0) to 4.5 W m⁻¹ K⁻¹ (z = 0.5, 1). This is accompanied by a transition to degenerate semiconducting behaviour leading to large power factors, S²/ρ = 2.5–3 mW m⁻¹ K⁻² and figures of merit, ZT = 0.25–0.33 at 773 K. Ti and Zr can be used to achieve positive Seebeck values, e.g. S = +150 μV K⁻¹ for 20% Zr at 773 K. However, the electrical resistivity, ρ_323K = 27–35 mΩ cm, remains too large for these materials to be considered useful p-type materials.

中文翻译：

---

Nb空位和NbCoSn–NbCoSb半霍斯勒热电材料的p型掺杂的影响†

半霍斯勒NbCoSn和NbCoSb具有良好的热电特性。这里，NbCo的调查_{1+ ý}的Sn _{1- ž}锑_Ž（Ý = 0，0.05; 0≤ Ž ≤1）固溶被呈现。此外，研究了使用Ti和Zr取代的NbCoSn的p型掺杂。Rietveld分析表明，逐渐形成了Nb空位，以补偿由NbCoSn中Sb的取代引起的n型掺杂。对于NbCo _{1+ y} Sn _{1- z} Sb _z样品（z> 0）。由于Nb空位而引起的质量波动紊乱将晶格热导率从10 W m ^-1 K ^-1（z = 0）大大降低到4.5 W m ^-1 K ^-1（z = 0.5，1）。这伴随着退化的半导体行为的转变，导致大功率因数，S ² / ρ = 2.5–3 mW m ^-1 K ^-2和品质因数，在773 K时ZT = 0.25–0.33。Ti和Zr可以是用于获得正的塞贝克值，例如对于773 K时20％Zr的S = +150μVK ^-1。但是，电阻率ρ_323K = 27–35mΩcm，对于这些材料而言，仍然太大以致于不能用作有用的p型材料。